1. Field of the Invention
The present invention relates to an energy conversion film and a quantum dot film that contain a quantum dot compound and a quantum dot film, and more particularly, to an energy conversion film and a quantum dot film which can act as a cut-off filter blocking light of a particular energy level using the light absorption and emission effects of quantum dots and can convert high energy light to low energy light.
2. Description of the Related Art
In order to address energy-related problems faced in recent years, research has been conducted into a variety of possibilities for the replacement of the long-used fossil fuels. In particular, extensive research has been conducted to utilize natural energy such as wind energy, atomic energy, solar energy and the like as alternatives to petroleum resources that are anticipated to be exhausted within a few decades. Solar cells use solar energy, which is an unlimited energy source, unlike other energy resources, and are environmentally friendly. Thus, a selenium (Se) solar cell was developed first in 1983, and currently silicon solar cells, polymeric solar cells (for example, dye-sensitized solar cell) and the like remain popular.
Such a solar cell employs, for the purpose of improving energy output, an optical coating to reflect the portion of a solar spectrum which is not converted to electricity. When no optical coating is used, solar light beyond the spectrum-responsive region (solar light of longer or shorter wavelength than the spectrum-responsive region) is absorbed by the cell, causing the cell temperature to increase, and at the same time reducing light conversion efficiency. In this regard, solar light is used after being filtered through a filter for light having a wavelength of 350 nanometers (nm) or greater (silicon solar cell), or a wavelength of 400 nm or greater (polymeric solar cell).
U.S. Pat. No. 5,449,413 discloses silicon solar cells, especially such solar cells used in spaceships, satellites and the like, in which light in the ultraviolet region of 350 nm or less and in the infrared region is reflected on the cell surface using a multilayer-structured doped semiconductor filter. However, the complicated structure and weight of the filter cause a rise in production costs and transfer costs, and thus, lead to reduced economic efficiency. In addition, the filter filters light in a shorter wavelength region by simple reflection and thus, the energy utilization efficiency is low.
Petterson et al. discloses in an article [Solar Energy Material and Solar Cell, 70, 203 (2001)], the use of polyester films as examples of filters that can be used in commercial polymeric solar cells. These films can be produced at relatively low costs, but they are only capable of blocking light of wavelengths of 400 nm or less.
Therefore, there is a need for a method of increasing the efficiency of energy utilization by blocking the solar light of a wavelength region which is not electrically converted in a solar cell and simultaneously converting the light to light having a wavelength that can be used in a solar cell.